SPC AC 030557
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CDT TUE OCT 03 2006
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MIDDLE MO VALLEY EWD
ACROSS THE SRN UPPER GREAT LAKES REGION...
...SYNOPSIS...
MID-LEVEL SHORT-WAVE TROUGH IS FORECAST TO MOVE EWD ACROSS THE NRN
PLAINS THIS PERIOD...THROUGH THE LARGE-SCALE MEAN RIDGE. THIS
FEATURE WILL BE ACCOMPANIED BY A BROAD ZONE OF ENHANCED WSWLY FLOW
/AROUND 50 KT AT MID-LEVELS/.
AT THE SURFACE...BAROCLINIC ZONE IS INITIALLY FORECAST TO EXTEND
FROM THE SRN UPPER GREAT LAKES REGION WWD ACROSS IA...AND THEN SWWD
ACROSS WRN KS. AN INITIALLY DIFFUSE SURFACE LOW IS FORECAST TO MOVE
EWD ALONG THIS BOUNDARY THROUGH THE DAY...AND SHOULD RESIDE INVOF
THE MID MO VALLEY BY LATE AFTERNOON. OVERNIGHT...THIS LOW SHOULD
DEEPEN/CONTINUE EWD...ALLOWING FRONT TO MOVE SWD ACROSS THE CENTRAL
PLAINS THROUGH THE END OF THE PERIOD.
...MID MO VALLEY EWD ACROSS THE SRN UPPER GREAT LAKES REGION...
THUNDERSTORMS SHOULD BE ONGOING AT THE START OF THE PERIOD OVER
PARTS OF THE MIDWEST/OH VALLEY REGION...LEAVING A RELATIVELY
UNDISTURBED WARM SECTOR ACROSS THE UPPER MIDWEST S OF WARM FRONT.
RELATIVELY MOIST BOUNDARY LAYER COMBINED WITH DAYTIME HEATING WILL
YIELD MODERATE DESTABILIZATION...WITH 2000 TO 3000 J/KG MEAN-LAYER
CAPE FORECAST ACROSS IA/SRN MN/SRN WI/NRN IL AND INTO LOWER MI/NWRN
OH. THOUGH WARM SECTOR SHOULD REMAIN LARGELY CAPPED...STORM
INITIATION IS FORECAST BY LATE AFTERNOON OVER SRN MN/CENTRAL AND SRN
WI. THESE STORMS SHOULD INCREASE IN COVERAGE AND SPREAD EWD INTO
LOWER MI THROUGH THE EVENING...AND PERHAPS REACH THE LOWER GREAT
LAKES REGION BY THE END OF THE PERIOD. MEANWHILE...ISOLATED STORMS
MAY ALSO DEVELOP BY LATE AFTERNOON/EARLY EVENING ALONG COLD
FRONT...FROM WRN IA SWWD INTO SERN NEB AND PERHAPS NERN KS.
WITH 50 KT MID-LEVEL WSWLY FLOW SPREADING EWD ACROSS THE WARM
SECTOR...SHEAR WILL BE SUPPORTIVE OF SEVERE/SUPERCELL STORMS. MOST
FAVORABLE LOW-LEVEL SHEAR SHOULD EXIST TO THE COOL SIDE OF THE WARM
FRONT...WITH POTENTIAL FOR A FEW TORNADOES ALONG THIS BOUNDARY
THROUGH THE EVENING. ELSEWHERE...LESS FAVORABLE LOW-LEVEL VEERING
BUT SUFFICIENT DEEP-LAYER SHEAR WILL SUPPORT A THREAT FOR LARGE HAIL
AND LOCALLY-DAMAGING WINDS. SEVERE THREAT SHOULD CONTINUE INTO THE
OVERNIGHT HOURS...AS INCREASING LOW-LEVEL JET SUPPORTS
PERSISTENT/FAIRLY WIDESPREAD CONVECTION ACROSS PARTS OF THE UPPER
MIDWEST AND THE UPPER GREAT LAKES REGION.
..GOSS/TAYLOR.. 10/03/2006
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z